Heathrow: Theresa May will not make final decision for at least a year while allowing Boris Johnson to speak out against third runway

Theresa May will not make a final decision on building a third runway at Heathrow for at least a year after announcing that she will give Boris Johnson and others the freedom to voice their opposition.

The Prime Minister told Cabinet colleagues that those with “strongly held views” would not be put in the “uncomfortable” decision on having to back the Government’s position if they do not agree with it.

She disclosed that the Government will announce its preferred choice for airport expansion at either Heathrow or Gatwick by the end of the month, but will not put the decision before Parliament until the “winter” of next year.

Her decision to give Cabinet ministers a “derogation” from collective responsibility, which requires them to support Government positions, will help her avoid high profile resignations.

Mr Johnson, the Foreign Secretary, and Justine Greening, the Education Secretary, are both strongly opposed to Heathrow while Greg Clarke, the Business Secretary, is opposed to Gatwick.

However the Prime Minister made clear that the “special derogation” will be subject to “a number of important caveats” in a warning to her ministers not to go too far.

She said that ministers will be banned from campaigning “actively” against the Government over the issue and publicly criticising the decision-making process.

Ministers will also be barred from speaking against the Government’s position in the Commons, and will only be able to voice their opposition for a limited period.

Mr Johnson has previously called Sir Howard Davies, the head of the Aiports Commission which recommended Heathrow, of being “myopic” and said that he is prepared to lie down in front of bulldozers to stop a third runway from being built.

Mrs May says in her letter: “If the decision is contrary to the previous public positions already taken by some colleagues, or directly affects colleagues constituencies, you will not be expected publicly to advocate the Government’s collective decision.

“You will be permitted, to restate longstanding views that are already a matter of public record and to pass on the views of your constituents if they are directly affected.”

She wanted to approach this in a mature way recognising that a number of ministers have long-held views on this issue and previously set out positionsNo10 spokesman on Theresa May's decision

Grant Shapps, a former chairman of the Conservative Party, yesterday criticised Mrs May for lifting collective responsility.

He told LBC Radio “It isn’t really acceptable to have ministers going their own way on this. “I’ve sat round that Cabinet table, you have to come to collective decisions and then you have to back them.”

The decision to put off the final decision surprised critics of Heathrow, who had been expecting the Government to hold a snap vote in Parliament. It comes after decades of delays over airport expansion by successive Labour and Conservative Governments.

David Cameron, the former Prime Minister, provoked fury from business leaders earlier this year when he delayed the decision on airport expansion amid concerns it would jeopardise Tory chances of winning the London mayorality.

Downing Street sources denied that there had been a delay in building the runway and insisted that was always going to be a consultation before the matter was put to Parliament.

Mrs May's comments suggest that she will refuse to hold a free vote on expanding Heathrow in the Commons, raising the prospect that ministers could take a leave of absence rather than vote against their will.

She adds in her letter: “It is important that we engage in the debate on this issue in a measured and balanced way. I do not want Ministers with a long record of opposing whichever scheme is chosen, or whose constituency is directly affected, to be put in an uncomfortable position.

“Equally all colleagues must respect he outcome of the decision making process. I am confident that this arrangement provides us with the right framework to allow us to do that.”

We have to decide whether to ignore the views of a million Londoners whose health will be affected by constant noise, or expand Gatwick, the environmentally responsible option where we can cap the number most affected by noiseStewart Wingate, Gatwick chief executive

A Downing Street source said: "As the Prime Minister said in her letter the sub committee meeting will decide upon a preferred scheme later this month."

It comes as the Government is facing the prospect of a rebellion from Conservative MPs in the South East if it pushes ahead with a third runway at Heathrow.

Zac Goldsmith, the Conservative MP for Richmond Park, has said he will resign his seat and run as an independent if the Government supports expanding Heathrow.

He will be supported by Tania Mathias, the Conservative MP for Twickenham, and his local Conservative constiuency association. Mrs Mathias, who was elected last year, said: “Zac is doing the honourable thing by committing to his pledge and I fully support him in that.”